Instrument Flying Handbook Glossary (pt. 5)

Microwave landing system (MLS)

A precision instrument approach system operating in the microwave spectrum which normally consists of an azimuth station, elevation station, and precision distance measuring equipment

Mileage breakdown

A fix indicating a course change that appears on the chart as an “x” at a break between two segments of a federal airway

Military operations area (MOA)

Airspace established for the purpose of separating certain military training activities from IFR traffic

Military training route (MTR)

Airspace of defined vertical and lateral dimensions established for the conduct of military training at airspeeds in excess of 250 knots indicated airspeed (KIAS)

Minimum altitude

An altitude depicted on an instrument approach chart with the altitude value underscored

Minimum crossing altitude (MCA)

The lowest allowed altitude at certain fixes an aircraft must cross when proceeding in the direction of a higher minimum en route altitude (MEA)

Minimum descent altitude (MDA)

The lowest altitude (in feet MSL) to which descent is authorized on final approach, or during circle-to-land maneuvering in execution of a nonprecision approach

Minimum en route altitude (MEA)

The lowest published altitude between radio fixes that ensures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes

Minimum obstruction clearance altitude (MOCA)

The lowest published altitude in effect between radio fixes on VOR airways, off-airway routes, or route segments, which meets obstacle clearance requirements for the entire route segment and which ensures acceptable navigational signal coverage only within 25 statute (22 nautical) miles of a VOR

Minimum reception altitude (MRA)

The lowest altitude at which an airway intersection can be determined

Minimum safe altitude (MSA)

The minimum altitude depicted on approach charts which provides at least 1,000 feet of obstacle clearance for emergency use within a specified distance from the listed navigation facility

Minimum vectoring altitude (MVA)

An IFR altitude lower than the minimum en route altitude (MEA) that provides terrain and obstacle clearance

Minimums section

The area on an IAP chart that displays the lowest altitude and visibility requirements for the approach

Missed approach

A maneuver conducted by a pilot when an instrument approach cannot be completed to a landing

Missed approach point (MAP)

A point prescribed in each instrument approach at which a missed approach procedure shall be executed if the required visual reference has not been established

Mixed ice

A mixture of clear ice and rime ice

MM

Middle marker

Multi-function display (MFD)

Small screen (CRT or LCD) in an aircraft that can be used to display information to the pilot in numerous configurable ways

National Airspace System (NAS)

The common network of United States airspace—air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information; and manpower and material